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<TITLE> Bs &rarr &Phi &Phi BR </TITLE>
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<H1 style= "color:blue;" > Measurement of B<sub>s</sub> &rarr &Phi &Phi Branching Ratio with 2.9 fb<sup>-1</sup> data</H1>
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This web page summarizes the results of the ratio of the BR(B<sub>s</sub><sup>0</sup> &rarr &Phi &Phi) to the BR(B<sub>s</sub><sup>0</sup> &rarr J/&psi &Phi). The measurement is done with  2.9 fb<sup>-1</sup> of Two Track Trigger data.
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The results have been approved by B Group Meeting as of June 19, 2009. 

<H4>A more  detailed description of the results can be found:</H4>
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<LI> Cdf Public Note 10064 <A HREF="cdf10064_BsPhiPhi_BR.pdf">here</A>
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<H2 style= "color:blue;">The analysis</H2>
The measurement consists in the evaluation of this ratio:
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where:
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<LI> N<sub>&Phi &Phi</sub>: number of  B<sub>s</sub> &rarr &Phi &Phi events;
<LI> N<sub>J/&psi &Phi</sub>: number of  B<sub>s</sub> &rarr J/&psi &Phi events;
<LI> &epsilon<sub>(B<sub>s</sub> &rarr &Phi &Phi)</sub>: efficiency of B<sub>s</sub> &rarr &Phi &Phi evaluated with Monte Carlo;
<LI> &epsilon<sub>(B<sub>s</sub> &rarr J/&psi &Phi)</sub>: efficiency of B<sub>s</sub> &rarr J/&psi &Phi evaluated with Monte Carlo;  
<LI> &epsilon<sub>&mu</sub>: muon efficiency.
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The optimized cuts for the two signals are summarized in the following table:
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The signal yields are shown in the figures:
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<H3 style="color:RED;">The final result of the ratio is:</H3>
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from which, using the Branching Ratio of B<sub>s</sub> &rarr J/&psi &phi, modified according
to the updated measurements of the ratio of production cross section of Bs and Bd
mesons, we have:
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<H2 ALIGN= CENTER >BR(B<sub>s</sub> &rarr &Phi &Phi) = [2.40  &plusmn 0.21(stat) &plusmn  0.27(syst) &plusmn 0.82(BR)] 10 <sup> &minus 5</sup></H2>
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where the last error is due to the uncertainty in the B<sub>s</sub> &rarr J/&psi &Phi Branching Ratio.


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The blessed figures are:


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<LI> KKKK invariant mass after reconstruction and trigger confirmation only  <A HREF="BlessedPlots/PhiPhi_BsMass_nocuts_Bless.eps"> .eps</A> <A HREF="BlessedPlots/PhiPhi_BsMass_nocuts_Bless.gif"> .gif</A>
<LI> <dl><dt>Sideband subtracted signal, Monte Carlo simulation and B<sub>s</sub> mass sidebands for the following observables:</dt>
   <dd> fit vertex &Chi<sup>2</sup><sub>xy</sub> in the plane transverse to the beam. <A HREF="BlessedPlots/PhiPhi_Bschi2_Bless.eps"> .eps</A> <A HREF="BlessedPlots/PhiPhi_Bschi2_Bless.gif"> .gif</A> </dd>
<dd> L<sub>xy</sub>, transverse decay length of B<sub>s</sub> candidates. <A HREF="BlessedPlots/PhiPhi_BsLxy_Bless.eps"> .eps</A> <A HREF="BlessedPlots/PhiPhi_BsLxy_Bless.gif"> .gif</A> </dd>
<dd> d0, Reconstructed impact parameter with respect the primary vertex of B<sub>s</sub> candidates. <A HREF="BlessedPlots/PhiPhi_Bd0_Bless.eps"> .eps</A> <A HREF="BlessedPlots/PhiPhi_Bd0_Bless.gif"> .gif</A> <dd>
<dd>d0<sup>&Phi<sub>max</sub></sup>, reconstructed impact parameter for the highest momentum &Phi .<A HREF="BlessedPlots/PhiPhi_d0max_Bless.eps"> .eps</A> <A HREF="BlessedPlots/PhiPhi_d0max_Bless.gif"> .gif</A> <dd> 
<dd> P<sub>T</sub><sup>K<sub>min</sub></sup>, minimum transverse momentum among the 4 kaons in the B<sub>s</sub> candidates decays. <A HREF="BlessedPlots/PhiPhi_Kptmin_Bless.eps"> .eps</A> <A HREF="BlessedPlots/PhiPhi_Kptmin_Bless.gif"> .gif</A> <dd>d0<sup>&Phi<sub>min</sub></sup>, reconstructed impact parameter for the lowest momentum &Phi .<A HREF="BlessedPlots/PhiPhi_d0min_Bless.eps"> .eps</A> <A HREF="BlessedPlots/PhiPhi_d0min_Bless.gif"> .gif</A> <dd>
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<LI> B<sub>s</sub> &rarr &Phi &Phi  signal yield <A HREF="defff1.jpg"> .jpg</A> <A HREF="BlessedPlots/PhiPhi_fit.eps"> .eps</A> <A HREF="BlessedPlots/PhiPhi_fit.pdf"> .pdf</A>
<LI> B<sub>s</sub> &rarr J/&psi &Phi  signal yield <A HREF="BlessedPlots/JPsiPhi_fit.jpg"> .jpg</A> <A HREF="BlessedPlots/JPsiPhi_fit.jpg"> .eps</A> <A HREF="BlessedPlots/JPsiPhi_fit.pdf"> .pdf</A>
<LI>  B<sub>s</sub> &rarr J/&psi &Phi  signal yield exclusively triggered by dispaced track trigger. <A HREF="BlessedPlots/BsJpsiPhi_noJPSI_PR2.jpg"> .jpg</A> <A HREF="BlessedPlots/BsJpsiPhi_noJPSI_PR2.jpg"> .eps</A> <A HREF="BlessedPlots/BsJpsiPhi_noJPSI_PR2.pdf"> .pdf</A>
<LI> CMX muon efficiency  <A HREF="BlessedPlots/eff2.jpg"> .jpg</A> <A HREF="BlessedPlots/Effmu_vs_pt_10_stdgr_nostat.eps"> .eps</A> <A HREF="BlessedPlots/Effmu_vs_pt_10_stdgr_nostat.pdf"> .pdf</A> 
<LI> CMP muon efficiency  <A HREF="BlessedPlots/eff1.jpg"> .jpg</A> <A HREF="BlessedPlots/Effmu_vs_pt_06_stdgr_nostat.eps"> .eps</A> <A HREF="BlessedPlots/Effmu_vs_pt_06_stdgr_nostat.pdf"> .pdf</A> 
<LI> Invariant Mass for the highest momentum K<sup>+</sup>K<sup>-</sup> pairs for B<sub>s</sub> &arr &Phi &Phi candidates.<A HREF="BlessedPlots/Phi1_mass.eps"> .eps</A> <A HREF="BlessedPlots/Phi1_mass.gif"> .gif</A> 
<LI> Invariant Mass for the lowest momentum K<sup>+</sup>K<sup>-</sup> pairs for B<sub>s</sub> &arr &Phi &Phi candidates.<A HREF="BlessedPlots/Phi2_mass.eps"> .eps</A> <A HREF="BlessedPlots/Phi2_mass.gif"> .gif</A>
<LI> Sideband subtracted  K<sup>+</sup>K<sup>-</sup> pair mass (two entries for candidates). <A HREF="BlessedPlots/PhiPhi_phimass_Bless.eps"> .eps</A> <A HREF="BlessedPlots/PhiPhi_phimass_Bless.gif"> .gif</A>
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<H2 style="color:blue;"> Theory Prediction </H2>
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<LI>B. Souza de Paula, Y. Xie; LHCb's sensitivity to New CP Violating Phases in the decay B<sub>s</sub> &rarr &Phi &Phi, LHCb public <A HREF="lhcb-2007-047.pdf">Note</A>.
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<H2 style="color:blue;"><A HREF="http://www-cdf.fnal.gov/physics/new/bottom/040408.blessed-bsphiphi/"> Previous Result </A></H2>
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